The Board announced that Brii Biosciences Limited's strategic partners, Vir Biotechnology, Inc. and VBI Vaccines, Inc. presented results from multiple clinical studies for the treatment and prevention of chronic hepatitis B viral infection at the European Association for the Study of the Liver Congress 2023 that further support the clinical evaluation of assets of the Company as a potential best-in-class functional cure for chronic HBV infection. In a late-breaker oral presentation, Vir announced 24-week follow-up data from a Phase 2 trial that demonstrated when VIR-2218 (BRII-835) was given for 24 or 48 weeks on top of a course of up to 48 weeks of pegylated interferon alpha ("PEG-IFN-a"), 26% (8/31) of virally suppressed participants with chronic HBV achieved hepatitis B surface antigen ("HBsAg") loss at end of treatment. In another oral presentation, Vir announced 48-week post-treatment data from Part A of the Phase 2 Monoclonal Antibody siRNA Combination against Hepatitis B trial.

VIR-2218 (BRII-835) and VIR-3434 (BRII-877) as combination treatment for chronic HBV infection resulted in 2.7-3.1 log10 IU/mL decrease in HBsAg levels following five or 12 weeks of combination treatment with 90% of participants achieving HBsAg less than 10 IU/mL at the end of this short treatment. In particular: The majority of participants met the criteria for discontinuing nucleotide reverse transcriptase inhibitor ("NRTI") therapy because they achieved all of the following: HBsAg less than 100 IU/mL and at or greater than 1 log10 IU/mL reduction from baseline HBsAg level; HBV deoxyribonucleic acid below the lower limit of quantification; and Hepatitis B Envelope Antigen-negative and Alanine aminotransferase at or less than twice the upper limit of normal. 67% (4/6) of those participants remained off NRTI therapy as of the last available follow up.

Combination treatment with VIR-2218 (brII-835) andVIR-3434 (BR II-877) was generally well tolerated and associated primarily with mild adverse events. All treatment-related adverse events were Grade 1, with no study discontinuations. In a poster presentation, Vir highlighted the single dose pharmacokinetics of VIR-3434 (BRII-877) from a Phase 1 clinical trial in patients with chronic HBV infection, with data supporting continued evaluation of VIR-3434 (BRII-877).

In particular: The higher and most durable free VIR-3434 (BRII-877) exposure was observed with the 300 mg dose, regardless of baseline HBsAg level. Other doses evaluated include 6 mg, 18 mg and 75 mg. VIR-3434 (BRII-877) has a shorter terminal half-life and was cleared faster in participants with higher baseline HBsAg.

In addition, VBI presented follow-up data in a subset of participants from the pivotal Phase 3 study, PROTECT, up to 3.5 years after completion of immunization with PreHevbrio ®, a prophylactic 3-antigen HBV vaccine, to determine the magnitude and duration of immune response. PreHevbrio consists of the same recombinant HBV surface antigens, Pre-S1, Pre-S2 and S, in virus-like particles, used in BRII-179 (VBI-2601). In particular: At all measured timepoints, participants immunized with PreHevbrio had significantly higher (P<0.0001) mean HBsAg antibody titers as compared to those who were immunized with Engerix-B®.

The data highlight that PreHevbrio induced T-cell responses against Pre-S1 and Pre-S2 proteins that correlated with high anti-HBs titers. At 3.5 years follow up, the mean anti-HBs titers in participants vaccinated with PreHevbrio were 5.1x higher than those vaccinated with Engerix-B (1287.2 vs. 253.7 mIU/mL) suggesting that T-cell responses of PreHevbrio may contribute to long lasting and strong humoral immune responses and greater durability compared with Engerix-B. As part of the Company's unique approach to develop a functional cure for HBV, the Company and its partners are progressing multiple studies, including BRII-835 (VIR-2218) and BRII-179 (VBI-2601) combination, BRII-179 and PEG-IFN- combination, BRII-835 (VIR-2218), BRII-877 (VIR-3434) with or without PEG-IFN-, and BRII-835 (VIR-2218) and/or BRII-877 (VIR-3434) in combination with other agents.

To date, approximately 390, 240 and 180 subjects have been treated with BRII-835 (VIR-2218), BRII-877 (VIR-3434), and BRII-179 (VBI-2601), respectively.